Control of vertical banks of oil burners



April 1968 E. c. MCKENZIE 3,378,202

CONTROL OF VERTICAL BANKS OF OIL BURNERS Filed Dec. 7, 1965 2 Sheets-Sheet 1 5' Edwin Charles Mc Kenzie W l A Home y April 16, 1968 E. c. M KENZIE 3,378,202

CONTROL OF VERTICAL BANKS OF OIL BURNERS Filed Dec. 7, 1965 2 Sheets-Sheet 9a 6a 8a United States Patent 3,378,202 CONTROL OF VERTICAL BANKS OF OIL BURNERS Edwin C. McKenzie, London, England, assignor to Babcock & Wilcox, Limited, London, England, a

corporation of Great Britain Filed Dec. 7, 1965, Ser. No. 512,077 4 Claims. (Cl. 239-76) ABSTRACT OF THE DISCLOSURE An arrangement whereby liquid fuel supplied from a common source is equally distributed between vertically spaced horizontal rows, each containing a plurality of burners. This is accomplished by eliminating the pressure differences due to the static head corresponding to the elevation of each burner row. Each row of burners is associated with a control device which includes a fuel flow regulating valve responsive to the difference between fuel pressure in that row and a predetermined pressure value. An alternate arrangement uses a difference in fuel flow rather than pressure to actuate the regulating valve.

This invention relates to liquid fuel burning apparatus having vertically separated liquid fuel burners and is especially concerned with the control of fuel to the burners.

It has been proposed to arrange liquid fuel burners in vertically spaced horizontal rows each containing a plurality of burners. When, as is often desirable, all the burners are supplied from a common source of fuel, it will normally happen that the pressure at the burners in an upper row is less than that in the bottom row by an amount depending on the density of the liquid fuel and the vertical distance between the rows. With identical fuel burners the quantity of fuel delivered from the burners of the upper row is less than that delivered from the burners of the lower rows by an amount which becomes proportionately greater as the boiler load is reduced. Since the flow of combustion air to the burner is not affected by the height of the burner, an effect of the differences between the heights of the burners will be that the supply of fuel to some of the burners will be deficient or excessive, so that either fuel is wasted or the flame falls short of its optimum characteristics.

According to the present invention, there is provided liquid fuel burning apparatus comprising a plurality of vertically separated liquid fuel burners, means for supplying the burners with liquid fuel from a common supply means, and control means for controlling the rate of discharge of fuel from the burners so that, for any burner, the ratio of the rate of discharge of fuel to the rate of discharge of combustion air is the same, or approximately the same, as that for any other burner.

By way of example, embodiments of the invention will now be described with reference to schematic figures of the accompanying drawing in which:

FIGURE 1 indicates liquid fuel burner apparatus in which the proportioning of flow of liquid fuel to various burners can be varied during operation;

FIGURE 2 indicates further liquid fuel burner apparatus in which the proportioning of flow of liquid fuel to various burners can be varied during operation;

FIGURE 3 indicates liquid fuel burner apparatus in which the means for proportioning the flow of liquid fuel to the various burners is fixed; and

FIGURE 4 indicates further liquid fuel burner apparatus in which the means for proportioning the flow of liquid fuel to the various burners is fixed.

In the drawing, each figure shows twelve burners B,

the four burners B1 being disposed in a horizontal upper row and connected in parallel to a common delivery tube T1, the four burners B3 being disposed in a horizontal lower row and connected in parallel to a common delivery tube T3, and the four burners B2 being disposed in a horizontal row between the other rows and connected in parallel to a common delivery tube T2. The three delivery tubes are supplied with liquid fuel from a common source The apparatus indicated in each figure also includes control means for controlling the rate of discharge of fuel from the burners so that for any burner, the ratio of the rate of discharge of fuel to the rate of discharge of combustion air is the same, or approximately the same, as that for any other burner.

In FIGURE 1, the control means includes three control devices D1, D2 and D3 associated respectively with the tubes T1, T2 and T3. Each device D includes a valve 5, the setting of which is determined by the bar 6 and varies in accordance with variations in the pressure at the end of the corresponding tube T, which pressure is a parameter characteristic of the flow conditions within the tube. The pressure is detected at the pressure responsive device 7 and the control elements 8 exerts force on the bar 6 that is proportional to the pressure measured in the device 7. The control element 9, which is representative of a fixed predetermined pressure, also exerts a force on the bar 6. The setting of the valve 5 is thus dependent upon the difference between actual pressure at the device 7 and a predetermined value and the setting is automatically adjusted to act to maintain this difference at the desired value. It will be realized that this difference may be varied for all the devices D automatically as rate of fuel supply from the source 4 varies since the expected pressure drop along each line T may vary with the rate at which fuel is supplied to the lines T.

The arrangement indicated in FIGURE 2 differs from that indicated in FIGURE 1 essentially in the nature of the parameter that is characteristic of the flow conditions within the tube. In this arrangement, a flow meter 10 is included in each tube T and the element 8a is such as to exert a force on the bar 6a that is dependent upon the rate of flow. The force exerted by the element 9a, again, is representative of a given predetermined rate of flow.

In the arrangements that have been described, the control means is such that the rates of flow to the various burners may be adjusted during operation by varying the predetermined setting of pressure or flow by means of the control element 9 or 9a. In the embodiments shown in FIGURES 3 and 4 the control means are fixed so that theywill produce a particular desired proportioning of the flow of fuel from the burners only at a given rate of supply of fuel from the source 4.

In the embodiment of FIGURE 3, each burner is provided with a flow restrictor in the form of an orifice plate through which fuel flows to the burner. The orifice plates for the burners in any row are all the same but the cross-section of the orifices increase from the lowermost row upwardly. The arrangement indicated in FIGURE 4 differs from that of FIGURE 3 essentially in that a flow restrictor 12 is provided in each row rather than for each burner. Again, the resistance offered by the flow restrictors increases from the lowermost row upwardly as shown by orifices 12A, 12B and 120.

In the embodiments that have been described the burners are arranged in a plurality of rows with the same number of burners in each row and this arrangement is especially useful when the liquid fuel burning apparatus is mounted on the wall of a vapor generator. It will be realized, however, that other burner arrangements might be adapted. Burners might be arranged singly one above another, for instance, or successive vertically spaced rows might include different numbers of burners.

I claim:

1. A liquid fuel burning apparatus for use in supplying fuel to a furnace comprising a plurality of liquid fuel burner means arranged at different elevations, common supply means for supplying liquid fuel to said burner means, a separate delivery tube associated with the burner means at each elevation and connected for flow of liquid fuel from said supply means to each of said burner means, and means for substantially equalizing the rate of flow to all of said burner means by fluid flow rate adjustment to the burner means at each elevation, a separate control device associated with each of said delivery tubes, including a valve disposed in each of said delivery tubes, an actuator connected to said valve, said actuator being responsive to the difference between the value of a separate parameter and a predetermined value, said separate parameter being directly sensed downstreamof said valve at each corresponding elevation and being characteristic of fuel flow conditions through the corresponding separate delivery tube.

2. Liquid fuel burning apparatus according to claim 1 wherein said fuel burner means includes a row of fuel burners connected in parallel to the corresponding delivery tube.

3. Liquid fuel burning apparatus according to claim 1 wherein said parameter is the fuel pressure and said predetermined value is representative of a predetermined pressure.

4. Liquid fuel burning apparatus according to claim 1 wherein said parameter is fuel flow into the delivery tube and said predetermined value is representative of a predetermined fuel flow.

References Cited UNITED STATES PATENTS 471,182 3/1892 Merrill. 2,060,844 11/ 1936 Adlam 2379 2,212,285 8/1940 Ayers 236-92 2,430,264 ll/l947 Wiegand et al. 123-119 2,540,778 2/1951 Dickey 23626 2,676,461 4/1954 Gove 15836 X 2,705,046 3/ 1955 Schroeder 158-36 2,960,155 11/1960 Bartz 158-36 FOREIGN PATENTS 760,406 10/ 1956 Great Britain. 880,141 10/1961 Great Britain. 980,404 11/ 1965 Great Britain.

FREDERICK KETTERER, Primary Examiner. 

